ykpamcfg (1) - Linux Manuals

ykpamcfg: Manage user settings for the Yubico PAM module


ykpamcfg - Manage user settings for the Yubico PAM module


ykmapcfg [-1 | -2] [-A] [-p] [-i] [-v] [-V] [-h]



use slot 1. This is the default.


use slot 2.

-A action

choose action to perform. See ACTIONS below.

-p path

specify output file for, default is ~/.yubico/challenge

-i iterations

number of iterations to use for pbkdf2 of expected response


enable verbose mode.


display version and exit


display help and exit



The PAM module can utilize the HMAC-SHA1 Challenge-Response mode found in YubiKeys starting with version 2.2 for offline authentication. This action creates the initial state information with the C/R to be issued at the next logon.

The utility currently outputs the state information to a file in the current user's home directory (~/.yubico/challenge-123456 for a YubiKey with serial number API readout enabled, and ~/.yubico/challenge for one without).

The PAM module supports a system wide directory for these state files (in case the user's home directories are encrypted), but in a system wide directory, the challenge part should be replaced with the username. Example : /var/yubico/challenges/alice-123456.

To use the system-wide mode, you currently have to move the generated state files manually and configure the PAM module accordingly.


First, program a YubiKey for challenge response on Slot 2 :

$ ykpersonalize -2 -ochal-resp -ochal-hmac -ohmac-lt64 -oserial-api-visible
Commit? (y/n) [n]: y

Now, set the current user to require this YubiKey for logon :

$ ykpamcfg -2 -v
Stored initial challenge and expected response in '/home/alice/.yubico/challenge-123456'.

Then, configure authentication with PAM for example like this (make a backup first) :

/etc/pam.d/common-auth (from Ubuntu 10.10) :

auth  required        pam_unix.so nullok_secure try_first_pass
auth  [success=1 new_authtok_reqd=ok ignore=ignore default=die] pam_yubico.so mode=challenge-response
auth  requisite       pam_deny.so
auth  required        pam_permit.so
auth  optional        pam_ecryptfs.so unwrap


Report ykpamcfg bugs in the issue tracker: https://github.com/Yubico/yubico-pam/issues



The yubico-pam home page: https://developers.yubico.com/yubico-pam/

YubiKeys can be obtained from Yubico: http://www.yubico.com/